This research program seeks to define the neuroanatomical maturation of the caudate nucleus with emphasis on the early postnatal period of synaptogenesis. A substantial number of experimental findings exists on the anatomy, biochemistry and physiology of the fully matured caudate nucleus and other basal ganglia. These point to their participation in both motor function and integrated behavior. It is our belief that the caudate nucleus provides a convenient model within the central nervous system to study the development of integrated synaptic connectivity by defining the temporal changes in synaptc organization and the emergence of certain enzymatic activities related to postsynaptic receptor sites during postnatal maturation of the brain. To test this belief, we propose to interrupt known connections to the caudate nucleus in the neonate surgically and to observe the results of such manipulations on subsequent development by histochemical and electron microscopic methods. We feel that such information is basic to further understand the role of the caudate nucleus in the development of normal and disordered brain function.